The purpose of this research is to explore possible neurochemical mechanisms underlying the behavioral effects produced by methaqualone. Though methaqualone is one of the ten most highly abused drugs today, there is a dearth of published basic research on the compound. The proposal builds upon one solid behavioral effect of the drug, its anticonvulsant properties and outlines studies designed to delineate possible neurochemical factors underlying tolerance, cross-tolerance dependence and withdrawal from methaqualone. Specifically interactions between methaqualone, methadone, alcohol, and marihuana (delta 9 tetrahydrocannabinol) on seizure susceptibility and brain biogenic amine systems will be studied. Sensitive radioisotopic, spectrophoto- fluorometric, chromatographic and differential centrifugation techniques coupled with a well-characterized behavior (audiogenic seizure susceptibility) should allow accurate correlations to be made between amine changes and behavioral manifestations.